Current ground-based observatories, Advanced LIGO [1]}, Advanced Virgo [2]} and KAGRA [3]} have sensitivity between approximately \(20\; {\rm Hz}\)  and \(\sim 2000 \; {\rm Hz}\) .
In the coming years, these observatories will continue to run a series of
increasingly sensitive observing runs, with lower frequency sensitivity
reaching no lower than \(10\; {\rm Hz}\)  [4]}.
It is expected that these runs will yield numerous observations of binary neutron star mergers, and hopefully numerous multimessenger observations [4]}, with which powerful tests of the speed of gravity can be performed.
However, to perform tests outside of this frequency range we must wait for the next generation of gravitational-wave observatories, expected to become operational in the 2030s.
The third generation of ground-based observatories, Einstein Telescope [6]} and Cosmic Explorer [7]}, will increase overall sensitivity, and increase the range of sensitive frequencies, covering from \(\sim 1\; {\rm Hz}\)  up to \(\sim 10^4\; {\rm Hz}\) .
Perhaps of most interest in this context though are the proposed space-based observatories, LISA [8]} and TianQin [9]}, which will cover a range of frequencies inaccessible from the ground, covering \(\sim 10^{-4}\; {\rm Hz}\)  to \(\sim 10^{-1}\; {\rm Hz}\) .
